Improvement in door-locks



` i; .s ,5mm hneln .i Gitta. its# Westera-w "mi" rf R. MCDOWELL, OF LAMBERT VILLE, -NEW JERSEY Letters .Patent N 88,57 7,' dated April 6, 1869.

' IMPROVEMENT DOOR-LOCKS.

The Schedule referred ton these Letters Patent and making part o; the same,

To alll whom 'it magg concern:

Be it known 4that I, R. McDoWELL, of Lambert-.- ville, in the' county of lHunterdomin the State of N ew Jersey, have invented a new and useful Improvement in Locks for Doors; and I do `hereby declare that the following isa full, clear, and exact description ot' the Construction andoperation of the same, reference being had to the accompanying drawings, makiuga part of this specification, iii which- Figure 1 is a front elevation of' one of the said im'- proved locks, and v Figure 2 the same lock, having the front coveringplate'removed therefrom, like letters of 'reference indicating the same parts in bot-h'iigures.

The object of my improvement is, to render the key by which the door is locked, from the inside of the building or room, a reliable security against unlocking the doen by any key applied from theiotside'.

My invention consists, substantially as hereinafter described and specified, in providing the outside and the inner-side covering-plates, respectively, of the lock with a distinct, or separate key-hole for the same key, and corresponding notchesand projections on the edge of the bolt, so constructed and arranged that the same key will lift the tumbler and operate thebolt, when used in either of the said key-holes, in connection with a'slightly oval ring, rigidly projecting from the edge of the tumbler, and surrounding the key-hole of the inner-side plat-e ofthe lock, so that the said key, when introduced and operated, will always bear with the end of its radial portion against the inner edge of the said ring', and thus raise and lower the tumbler, and also prevent the bolt from being operated by any key introduced and operated in the key-:hole on the outer side of the building or room.

Referring to the drawings,

A B is the body ot the lock, a' being its inner-side plate and b its outer-side plate;

C, tire bolt;

D, 4the tumbler; and E, the key.

'lhe outer-side key-hole b" is made about half-way between the inner-side key-hole a and the outer end of the body A B of the lock, andthe respective notches and projections cf c' and c c", in the' edge of thebolt C, are each made so as to be acted uponby the key,

in, the usual manner, excepting that the projections c y c" are made much longer than heretofore, for the purpose hereinafter explained.

The tumbler D turns upon a pin d', and when operated by the key in either of the two key-holes b" a, alternately releases and holds the bolt 0,- i'n the usual manner.

At one edge of the said tumbler D, there is a large oval ring dformed, which surrounds the inner-side key-hole a.

The longer inside diameter of the ring d" is equal to t vice 'the length of the radial part of the proper key, and this longer dia-meter, being nearly parallel with the len, z,th ot the said tumbler D, the latter will be raised and lowered when'the key is operated, for the purpose of moving the bolt C.

Operation.

When the key E is inserted in the key-hole a, and operated, the extreme endlothe radial part immediately comes in contact with the inside edge ot' the 'ling d", and eventually lit'tsrthe tumbler, as indicated by the dotted lines 2,'and drops the catch ofthe tumbler into'appropriate stop-notch'iu the bolt C, the slot in the end of the radial portion ofthe key, at the same time, receiving the inner-edge of the projections c" c", and moving the bolt O. f

The key being left in thelock, after locking the door, it will be in icontact either with the ring d,'at any point between the ends ot' the projeciious c d' otl the bolt C, as indicated at E and the dotted line x, or in contact with .both the ring cl.ot' thetumbler D, and the tin-ward projection c" of the bolt O, as indicated by the dotted lilies at y. Y

Now, it' a key be introduced through .the outside key-hole-b, for the purpose of moving back the bolt O, its radial portion will tirst come in contact with the tumbler, as indicated4 by the faint lines x', and be arrested, if the radial portion of the inside key E be in any ofthe positions below and between the projections c 0"; but it'the said key E be left in the position indicated by the dotted line y, the outside key will lit't the tumbler D, and reach the position indicated by the;

faint lines Q where it will be arrested by the projection c of the bolt C, becausethe inside key E, being in the position indicated by the dotted lines I1, will eifectually prevent the bolt C from being moved backward. It will therefore be seen that this lock cannot be opened from the outer side of ythe door,- if lthe legitimate key be left in the-key-hole on the inner side.

This device is simple, effective for the purpose, and not liable to get out of orderii'oni use.

Having thus' fully described my improvement, lVliat I claim as new therein, and desire to secure by Letters Patent,.is confined to the following, viz:

The two separate key-holes a, b", in the plates a'b, respectively, with the corresponding projections c c i and c' c', on the bolt'C, and the ring d" of the tumbler D, the said part-s being constructed and arranged to be operated and secured by the legitimate key E, sub-l stantially as and for the purpose described.

R. MCDOWELL. 

